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Old 04-16-2012, 02:35 PM   #1
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Low Refrigerant charge ?


410a


88 degrees outside air
73 degree return air
62 degrees supply air out the vents


95lbs pressure on the suction
310lbs pressure on the high side

96 degree high side pipe temp
80 degrees low side pipe temp


House is cooling, but I feel I may have a tinnnnnnny leak that a lost some charge over winter, I could of swore the cooling effecineny was wayyy better last summer.

I know just enough to be dangerous, but I feel the charge might be low? Correct?

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Old 04-16-2012, 02:41 PM   #2
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Old 04-16-2012, 02:43 PM   #3
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Low Refrigerant charge ?


Quote:
Originally Posted by alecmcmahon View Post
410a


88 degrees outside air
73 degree return air
62 degrees supply air out the vents


95lbs pressure on the suction
310lbs pressure on the high side

96 degree high side pipe temp
80 degrees low side pipe temp


House is cooling, but I feel I may have a tinnnnnnny leak that a lost some charge over winter, I could of swore the cooling effecineny was wayyy better last summer.

I know just enough to be dangerous, but I feel the charge might be low? Correct?
Looking at that pressure/temperature chart at 85 degrees the pressure would be 254 which would be approximately twice as high as a normallly charged and functioning 410-A system.
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Old 04-16-2012, 02:44 PM   #4
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Low Refrigerant charge ?


theremostatic expansion valve or piston orifice metering device?
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Old 04-16-2012, 02:46 PM   #5
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theremostatic expansion valve or piston orifice metering device?

orifice
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Old 04-16-2012, 02:48 PM   #6
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Low Refrigerant charge ?


Have a thermometer? Check the air temp at the return grill and then up in the closest supply vent to the unit.

It's called a temperature split or differential. Can tell what's going on, somewhat, just by those temps.
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Old 04-16-2012, 02:51 PM   #7
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Quote:
Originally Posted by alecmcmahon View Post
orifice
Superheat charging.

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Old 04-16-2012, 02:52 PM   #8
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Have a thermometer? Check the air temp at the return grill and then up in the closest supply vent to the unit.

It's called a temperature split or differential. Can tell what's going on, somewhat, just by those temps.
73 degrees at return grill

about 65 degrees coming out of the supply vent
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Old 04-16-2012, 02:57 PM   #9
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Low Refrigerant charge ?


A somewhat usual or average temperature differential would be 17-20 degrees. 65 degree supply air is too warm.

Are both the inside and outside coils clean? Must be clean in order to properly charge a system and the return air must not be restricted, clean or new filter.
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Old 04-16-2012, 03:00 PM   #10
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Quote:
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A somewhat usual or average temperature differential would be 17-20 degrees. 65 degree supply air is too warm.

Are both the inside and outside coils clean? Must be clean in order to properly charge a system and the return air must not be restricted, clean or new filter.
Unit was installed last spring, brand new.

filters clean, coils clean.

still suspecting low charge.

if leaking, i'll have to track down.
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Old 04-16-2012, 03:16 PM   #11
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Low Refrigerant charge ?


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Old 04-16-2012, 03:16 PM   #12
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Don't let one year old fool you into thinking the coils are clean, but I'll take your word for it.

Are you in hvac or just a homeowner? You're going to need nitrogen, gauges, plus the service valve wrench and an HFC leak detector.
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Old 04-16-2012, 03:18 PM   #13
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it ain't low charge

I was wondering if it might be overcharged being a fixed orifice and all, if the evaporator was flooding the first few circuits with straight liquid before saturation.

Very low if not 0 superheat.
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Old 04-16-2012, 03:18 PM   #14
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Quote:
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Don't let one year old fool you into thinking the coils are clean, but I'll take your word for it.

Are you in hvac or just a homeowner? You're going to need nitrogen, gauges, plus the service valve wrench and an HFC leak detector.
I work in HVAC, but im not a mechanic, I mostly work water cooled units / cooling towers / chillers in a building.

I only have 3 spots in mine line set where we brazed fittings in, checked all, didnt see any oil around them, but i'll do the bubble test later.

it hasnt ran since last summer ended, I figure if there were a leak, itd all be empty by now no?
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Old 04-16-2012, 03:23 PM   #15
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I work in HVAC, but im not a mechanic, I mostly work water cooled units / cooling towers / chillers in a building.

I only have 3 spots in mine line set where we brazed fittings in, checked all, didnt see any oil around them, but i'll do the bubble test later.

it hasnt ran since last summer ended, I figure if there were a leak, itd all be empty by now no?

Not really. You can have a very tiny leak where you may only need an ounce or two that may last for one or two entire seasons. Granted when it's running is when it'd leak the most.

Don't forget about the orifice O ring where the piston is. A lot of times you can simply tighten it down. Others, if the seal is melted as in when brazing in, you're going to need to perform a full recovery or pump down of refrigerant and open up the piston and change the ring.

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